Supporting brackets of the type disclosed in the present invention are adapted to be employed for the support of casement type windows or projection type windows, that is, for the support of windows to permit their pivotal movement about a vertical axis or a horizontal axis, and are also adapted to be connected between a conventional window frame and window sash, whether these structures be formed of metal, wood, PVC, or other structural material. The brackets are typically arranged to cause the pivotal axis of the window to move to and from the window frame so that when the window is open, both surfaces are accessible from the inner side of the window.
U.S. Pat. No. 3,345,777 to Anderberg et al discloses a supporting bracket which can be used on either the left or right hand side of a window. In actual practice, however, the axes of the various pivot pins are purposely misaligned so that the vent bar is intended to occupy a position parallel to, but laterally offset from, the median line of the track, as is more clearly shown in U.S. Pat. No. 2,784,459, also to Anderberg et al. The supporting bracket is disclosed as capable of occupying either one of two such offset positions. This enables the supporting bracket to be mounted at either end of a window frame and sash without requiring the manufacture of "right" and "left" pairs. By disposing the vent bar in a laterally offset position, the various pivotal axes are offset sufficiently that the bar moves freely and easily from its offset superposed position to its various angular positions.
Although the supporting bracket of Anderberg et al may be used on either side of a window, it must be mounted with special notice taken as to the proper misalignment of the vent bar with respect to the track. A supplier of such supporting brackets must provide a manufacturer of window frames with detailed offsetting specifications for locating a bracket with respect to a frame. Specially fabricated frames must then be accordingly drilled to locate the bracket in the left or right position depending on which side of the window the bracket is located. Thus, a two step process is required in which frames must be specially fabricated which can only be used with this specific supporting bracket. If the bracket is mounted such that the vent bar is not offset from the median line of the track, in other words is "in line" with the track, then movement of the hinge at angles to the track becomes difficult, if not impossible. As shown in FIG. 1, the tip of the vent bar tends to bind at the cap member if the vent bar is attempted to be moved in the direction A, caused in part by the vent bar crossing over the centerline of the track member. If movement is at all possible, it must use the compression of the weather-strip rather than the geometry of the cap to allow the window to open. In addition, the ability to laterally offset the vent bar results in insufficient containment of the end of the vent bar in the cap in its home position. The insufficient containment can result in "play" in the home position which can translate into air and water leakage from the weather-strip.
U.S. Pat. Nos. 4,689,852 and 4,718,144 to Buckley disclose an attempt at solving some of the above-described problems. Buckley discloses the use of a friction supported stay having a cap member and nose member sharing a corresponding asymmetrical shape designed to prevent the displacement of the nose from the cap member typical with heavy windows. Although a stay of this design can utilize window tooling for center mount installation, the stay is what is termed "handed", that is, there must be separately designed stays for the left hand side and the right hand side of a window (or top side and bottom side). This inevitably increases the complexity of installation. In addition, the stay of Buckley requires that the nose member be made of a plastics material and be riveted onto the bar. The cap member is also made of a plastics material and riveted onto the track. The application of a separate nose member increases the time to manufacture the stay, and thus increases the cost per stay. In addition, it has been found by some installers that the separately riveted nose member may on occasion become snagged on the cap member if the window is not closed properly.
Thus, there is a need for a supporting bracket or stay which can be used on either side of a window. There is further a need for a supporting bracket or stay which can utilize center mount installation on both sides of a window. There is further a need for a supporting bracket or stay which opens and closes smoothly without binding at the cap member or between the arms of the supporting bracket. There is further a need for a supporting bracket or stay which prevents any sash play. There is further a need for supporting bracket or stay which utilizes the geometry of the hinge to open and close the window rather than depending on the compression of the weather-strip which could create weather strip problems such as rolling over.